flightlogic

flightlogic

Well Known Member
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I often see blue stains near the caps if over filled on a hot day. This week, though, I was able to peel the blue stain off the wings like vinyl.
I called the city fuel office and asked if anyone had noticed a change in the dye content. No reply. Of course the concern is potential blockage.
Is it a non issue since the dye in the actual tank is always in suspension?
 
flightlogic said:
I often see blue stains near the caps if over filled on a hot day. This week, though, I was able to peel the blue stain off the wings like vinyl.
I called the city fuel office and asked if anyone had noticed a change in the dye content. No reply. Of course the concern is potential blockage.
Is it a non issue since the dye in the actual tank is always in suspension?
Click to expand...

If the fuel is expanding to the point where it's seeping out of the caps, I would be more concerned that the vents aren't venting. That's where the fuel should be coming out when expanding. I drove the FBO fuel truck in high school in FL and we would see this all the time. Try not refueling until you're ready to go. Against conventional wisdom, but it's how a lot of guys mitigated the problem. Shouldn't have to worry about water in the fuel in a dry climate like AZ. Also try servicing your fuel caps.

The dye is put in at the refinery.
 
The fuel was maxed out... to do a quick weight on scales data point.. so I knew it was going to leak. The left tank does a whoosh... when releasing the cap. Next on the list is checking the vent and airflow through it. Caps have new o rings and Dow 4 lubed frequently. BUT... point well taken to not top off until needed... here in AZ. Getting hot.
(in El Paso for hoist training today.... getting WINDY)
 
The excess dye problem has been noticed here in Canada as well... A fellow RV'er drained a fuel-tester cup's worth out of a full tank and had a fuel tester that looked like it had Windex in it it was so blue. It burned just like any other 100LL he's run so he didn't worry about it. But it got his attention!
 
It appears that annecdotal evidence is mounting. Small sample for sure... but it gets my attention. The vinyl like residue I peeled from the wings was not something I would ever want to see in the tanks.
Will be putting the tiny camera in the tanks for the immediate future to have a look see. I know dye comes from the refinery... but that doesn't mean it can't be screwed up.
 
I re-fueled the other day and thought it looked bluer than usual. I thought it must just be me....

Anyone know if they have switched dyes recently?
 
Blue Dye- Kinda long-

I have seen a couple instances where the dye color was darker than usual. In an extreme case one of my shop customers departed KNEW westbound in a Cessna 340 on a low IFR day, climbing thru 3000' both engines lost almost all power. According to the 2 experienced pilots on board engines never ran rough or completely stopped running they just stopped producing power. Moving the throttles, mixtures, fuel valves and pump switches didn't change anything. They were fortunate, when this problem started plane was in a good position to dead stick the ILS 28 at KMSY,(wx 400' & 2nm) approach controller was on the ball and everybody worked well together. After landing engines were idling normally and plane was able to taxi to ramp under its own power. I got there about 3 hrs later and checked all fuel filters, screens, vents, compressions, timing, air filters, ect ect. Plenty of fuel on board in all tanks but all sumps produced about 6 oz of extremely dark blue "fuel" on the the first draining and after that fuel color was the normal light blue. Fuel was put on at KNEW before takeoff so that vendor was notified and they checked their trucks and fuel farm and word was nothing unusual found. After putting everything back together engines started right up and ran normally. Did extensive ground runs at all power settings and found nothing. After running out of things to check I flew it the 90nm back to home base at 12500' with no issues. Plane went thru another round of troubleshooting after talking to tech support at Cessna, Continental, Ram and every wise old owl I could find and still nothing found(no access to Rocket Bob and the others back then). It got flown several more hrs over the airport with no issues and was put back to work. This was a nice low time business aircraft that flew around 150 hrs a year. I was involved with the Maint of this 340 for about 2 yrs before and 2 yrs after this event and it never had any unusual problems in this timeframe and never gave any hint of power interruption before or after. There was no cut and dried "smoking gun" but it had to be related to the fuel dye/color. This remains the biggest un solved mystery of my 35+ years in aircraft maintenance.

Don Broussard
RV 9 Rebuild in Progress
 
Don,
Thanks for sitting at the keyboard to recall the whole mystery.
I have put a request in to AOPA to see if other reports are showing up.
It is my guess that most fuel suppliers would end up at the same point, saying "no fault found". It is never in the interest of those on the ground...
It is always in the interest of us above the ground. We shall see where this may lead.....
 
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